Near infrared spectroscopy and aquaphotomics analysis of serum from mares exposed to the fungal mycotoxin zearalenone

Authors: VANCE, CARRIE - Mississippi State University; COUNSELL, KRISTEN - Mississippi State University; AGCANAS, LAUREN - Mississippi State University; Shappell, Nancy; BOWERS, SUSAN - Mississippi State University; WILLARD, SCOTT - Mississippi State University; RYAN, PETER - Mississippi State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/10/2016
Publication Date: 1/14/2017
Citation: Vance, C.K., Counsell, K., Agcanas, L.A., Shappell, N.W., Bowers, S., Willard, S.T., Ryan, P. 2017. Near infrared spectroscopy and aquaphotomics analysis of serum from mares exposed to the fungal mycotoxin zearalenone [abstract]. Reproduction, Fertility and Development. 29(1):160-161.

Interpretive Summary: .

Technical Abstract: Aquaphotomics is a branch of near infrared spectroscopy (NIR) in which bond vibrations from organic molecules and water create unique spectral absorbance patterns to profile complex aqueous mixtures. Aquaphotomics has been shown to detect virus infected soybean plants from extracts, classify probiotic bacteria and detect contamination of aquatic ecosystems. We have used aquaphotomics to characterize serum profiles from horses in various phases of the reproductive cycle such as estrus and diestrus. Because serum is a complex solution of biomolecules, various modes of serum processing (e.g. large protein removal for proteomics or mass spectrometry) may provide different NIR spectral profiles for quantitative analysis of specific compounds or their effects. Zearalenone is a fungal mycotoxin that may have estrogenic potential in mares and is found in feedstuffs. This study’s objectives were to: 1) establish NIR spectral profiles of serum and protein-precipitated serum (PPS) collected at peak estrus from mares; 2) determine if NIR profiles correlate to estrus E2 concentrations in serum or PPS; and 3) determine if NIR can detect differences in serum or PPS chemistry profiles of zearalenone treated mares. Mares were fed zearalenone daily at low (2mg, 2 mares, 5 cycles) and high (8mg, 1 mare, 3 cycles) concentrations, plus control (0mg, 1 mare, 3 cycles). Estrus cycles were monitored by ultrasound and serum hormone analysis. Serum collected on the day of peak estrus and E2 values determined by radioimmunoassay ranged from 0.02-16.87pg/ml. High and medium MW proteins were precipitated from 8 serum samples using a 2:1 acetonitrile:serum ratio, the extract was lyophilized and resuspended in 5x ET water to generate the initial serum concentration of components. Serum and PPS samples had NIR spectra collected in triplicate using a 1mm quartz cuvette and ADS FieldSpec®3 with fiber optic system. Chemometric analysis (Unscrambler®X vs. 10.4; CAMO Software) included Savitsky-Golay 1st derivative for inspection of spectral features, principal component analysis (PCA), and partial least squares regression (PLS) to investigate spectral correlation to E2 values and zearalenone treatment effects. NIR profiles of serum and PPS at estrus had distinct spectral features and 97% of PCA variance was described by PC-1. Using a PLS cross-validation (CV) regression model, RIA measured E2 vs. NIR predicted E2 validation metrics were better for spectra of serum (slope=0.89, SECV=1.92, R2=0.81, 3 factors) than spectra of PPS (slope=0.61; SECV=1.84, R2=0.76, 4 factors). Spectral predictions were poorest at the low threshold, E2=0.02 pg/ml. Similarly, PLS model validation metrics of zearalenone effects in serum (slope=0.88, SECV=1.26, R2=0.86) were also better than for PPS (slope=0.67, SECV=1.96, R2=0.66). In summary, NIR profiles of serum map E2 hormone levels during reproductive cycling, and these spectra may also have correlations that reflect exposure of mares to estrogenic toxins such as zearalenone.